AI Upscaling vs Normal Image Resizing
Making an image bigger sounds simple, but there are two very different ways to do it: ordinary resizing, which stretches the pixels you have, and AI upscaling, which predicts new detail. Here’s what each does, with a real example.
What ordinary resizing does
Standard resizing (bicubic or similar) calculates each new pixel as a smooth blend of its neighbours. Enlarge an image 4× this way and every original pixel becomes a soft 4 × 4 patch. Nothing is invented, so the result is honest but blurry: edges lose their crispness and textures turn to mush.
What AI upscaling does
An AI upscaler such as Real-ESRGAN has been trained on millions of pairs of low- and high-resolution images. It recognises patterns like edges, hair, fabric and line art, and draws the sharp detail those patterns usually have at higher resolution. It also reduces JPEG blockiness and noise along the way.
A real comparison
We took a 400 × 600 anime-style illustration and enlarged it 4× to 1,600 × 2,400 pixels, once with standard resizing and once with our Anime & Illustration Upscaler. With standard resizing, the outlines of the hair and the sword grip became soft and slightly blurred. The AI version kept clean, dark outlines in the hair, eyes and sword grip, and crisp highlights, as if the artwork had been drawn at the larger size.
Where AI helps most
- Small images you need bigger: old web graphics, thumbnails and avatars.
- Anime, cartoons and line art: clean outlines and flat colors are exactly what the anime model is trained for.
- Slightly soft or compressed photos: AI often removes JPEG artefacts while enlarging.
Where it can make things worse
- Tiny faces and small text: the AI may draw features or letters that look real but weren’t there.
- Heavily blurred or out-of-focus photos: there are no edges to sharpen, so the result can look painted.
- Evidence and documents: never use AI-enlarged images where exact detail matters, because added detail is a guess.
Which should you use?
To make an image smaller, always use ordinary resizing with Resize Image; AI adds nothing there. To make an image bigger, use the AI Image Upscaler for photos and the Anime & Illustration Upscaler for artwork. Both run on your device, so your image is never uploaded.